Molecular sieves are a commercially important class of crystalline materials. They have distinct crystal structures with ordered pore structures which are demonstrated by distinct X-ray diffraction (XRD) patterns. The crystal structure defines cavities and pores which are characteristic of the different species.
SSZ-23 is a molecular sieve material which has a unique two-dimensional channel system composed of intersecting 9- and 7-membered ring pores. SSZ-23 has been assigned structure type STT by the Structure Commission of the International Zeolite Association.
The composition and characteristic XRD pattern of SSZ-23 are disclosed in U.S. Pat. No. 4,859,442, which also describes the synthesis of the molecular sieve in the presence of an N,N,N-trialkyl adamantammonium cation structure directing agent.
SSZ-23 is useful in many processes, including various catalytic reactions. For example, U.S. Pat. No. 4,902,844 exemplifies the use of SSZ-23 as a catalyst in xylene isomerization reactions; U.S. Pat. No. 4,952,744 discloses that SSZ-23 is useful as a catalyst in the conversion of lower alkanols, such as methanol, to form gasoline boiling range hydrocarbons; U.S. Pat. No. 5,609,751 and U.S Patent Application Publication No. 2010/0160700 disclose that SSZ-23 can be useful as a catalyst for reforming naphthas to aromatics; U.S. Pat. No. 7,641,787 discloses the use of SSZ-23 as a catalyst in the reduction of NOx in flue gas streams exiting from fluid catalytic cracking (FCC) regenerators; and U.S. Pat. No. 7,858,059 discloses that SSZ-23 is useful as an adsorbent in hydrocarbon traps for the treatment of engine exhaust.
To date, however, the commercial development of SSZ-23 has been hindered by the high cost of the structure directing agent required for its synthesis and hence there is significant interest in finding alternative, less expensive means for the synthesis of SSZ-23.